In vivo forces and musculoskeletal loading conditions are frequently unknown in human fracture healing settings. Using patient anatomy, fracture geometry and fracture fixation from the BioBone cohort, Zachow and Trepczynski aim at unravelling the mechanical conditions at the site of a fracture. They focus on a detailed quantitative analysis of the mechanical boundary conditions in elderly or otherwise compromised patients. Their predictions will be verified by measuring the relative interfragmentary motion components (compression and shear) in vivo. They want to assess the occurring ranges of fracture motion during healing progression to be able to stratify the initial mechanical conditions derived from the fracture fixation treatment.